An organic light-emitting device has a structure in which a thin film comprising a fluorescent organic compound or phosphorescent organic compound is interposed between an anode and a cathode. By injecting electrons and holes (positive holes) from the electrodes into the device, excitons of the fluorescent organic compound or phosphorescent organic compound are generated, and light radiated when the excitons return to a ground state is utilized.
Further, the recent progress of the organic light-emitting device is remarkable, and is characterized in that a highly responsive, thin, and lightweight light-emitting device that can be driven at a low applied voltage and provides a high luminance and a variety of emission wavelengths can be made, which suggests the applicability to a wide variety of uses.
However, at present, an optical output of a higher luminance or light emission of a higher conversion efficiency is still required. Further, there still remain a large number of problems in terms of durability such as a time-dependent change due to long-term use and deterioration due to an atmospheric gas containing oxygen or to moisture. Moreover, when application to a full-color display or the like is attempted, emission of blue, green and red lights with high color purities is necessary, but these problems have not satisfactorily been solved yet.
As patent documents which disclose compounds comprising fluorene and fused rings, there are included Japanese Patent Application Laid-Open Nos. 2003-229273 and 2004-43349, but the patent publications have no specific description about the organic compound of an asymmetric molecular structure with a molecular structural formula comprising oligofluorene and a fused polycyclic aromatic group with four or more rings according to the present invention.